Both M-EAR models feature ACS’s patent-pending IRIS (Intelligent Resonance In Silicone) technology, created to maximise the musical potential of balanced armature drivers. IRIS construction methods allow precise acoustic tuning, fusing the crisp, open detail that characterises high-performance balanced armature IEMs with a musical warmth and fluidity that other manufacturers fail to match. Additionally, the M-EAR 4D incorporates a ported balanced armature design for the bass drivers, with a cavity in the silicone that is precisely balanced to the driver – this is unique to ACS.

Another ACS feature integrated in both M-EAR models is SSI (Sound Stage Imaging) – a tuning technique derived from ACS’s purpose-designed manifold technology. This widens the soundstage and creates more space around individual instruments and voices, enhancing sonic definition and the feeling of being present at a live musical performance.

The result, in the case of the M-EAR 2D, is a pair of discrete IEMs delivering taut, punchy bass, captivating midrange clarity and crisp, clean high-frequency detail, with no harmonic interference. Invest in the M-EAR 4D and the sonic return is even greater space, scale and dynamic expression.

An in-line microphone is included for hands-free convenience when making calls, but this is no ordinary miniature mic – it is a Knowles SiSonic MEMS-based microphone, selected as a result of ACS’s pro-audio experience for excellent wide-band voice reproduction in noisy environments.

To ensure a snug fit and superb noise isolation, the M-EARs come with six pairs of ear tips in three different sizes. Developed by ACS and made from memory foam, they slowly form to the shape of the ear canal to separate the listener from outside noise whilst providing excellent comfort. Thanks to the reduction in ambient noise, musical detail remains crystal clear even at lower volume levels